Vehicular hybrid drive system with battery arctic management

Abstract

A battery management for a hybrid drive system for a vehicle recovers input and output performance of a battery if the battery temperature is low. If the battery temperature is less than or equal to a predetermined value (or if the battery internal resistance is greater than or equal to a predetermined value), the battery needs to recover its input and output performance. Under this condition, the state of charge (SOC) of the battery is determined and compared with a predetermined value. The comparison result is used to determine whether the battery is capable of discharging or the battery needs charging. If SOC is greater than or equal to the predetermined value, a controller conducts forced discharge from the battery to operate an electric motor of the hybrid drive system in power mode. This forced discharge causes an increase ion the battery temperature, thus causing the battery to recover its input and output performance.

What is claimed is: 
     
       1. A hybrid drive system for a vehicle, comprising; a battery;   an electric motor powered by said battery;   sensors to sense parameters indicative of a state of said battery; and   a controller to input information of battery temperature of said battery and information of a state of charge (SOC) of said battery from said sensed parameters indicative of the state of said battery,   said controller being operative to conduct a forced discharge from said battery by establishing supply of electric energy from said battery to said electric motor when the battery temperature is less than or equal to a predetermined temperature value and the state of charge (SOC) of said battery is greater than or equal to a predetermined SOC value,   said controller being operative to conduct a forced charge to said battery from said electric motor by establishing supply of electric energy to said battery from said electric motor when the battery temperature is less than or equal to said predetermined temperature value and the state of charge (SOC) of said battery is less than said predetermined SOC value.   
     
     
       2. A hybrid drive system for a vehicle, comprising: a fuel powered engine;   a battery;   an electric motor powered by said battery, said electric motor being in driving relationship with said engine;   sensors to sense parameters indicative of a state of said battery;   sensors to sense parameters indicative of a state of said engine;   a controller to input information of a state of charge (SOC) of said battery from said sensed parameters indicative of the state of said battery,   said controller being operative to determine based on said sensed parameters indicative of the state of said engine whether or not said engine is being powered by fuel,   said controller being operative to conduct a forced discharge from said battery, by establishing supply of electric energy from said battery to said electric motor when the state of charge (SOC) of said battery is greater than or equal to a predetermined value, thereby to cause said electric motor to start up said engine unless said engine is being powered by fuel and to operate in power mode after starting up said engine.   
     
     
       3. The hybrid drive system as claimed in claim 2, further comprising: a continuously variable transmission (CVT) having an oil pump in driving association with said engine;   an electric motor for driving said oil pump; and   a sensor to sense oil temperature of oil within said oil pump;   wherein said controller is operative to conduct said forced discharge from said battery by establishing supply of electric energy from said battery to said electric motor for driving said oil pump when the sensed oil temperature is less than or equal to a predetermined temperature value.   
     
     
       4. The hybrid drive system as claimed in claim 2, wherein said controller is operative to conduct said forced charge operation when the state of charge (SOC) of said battery is less than said predetermined SOC value by establishing supply of electric energy from said battery to said electric motor to start up said engine and then establishing supply of electric energy to said battery from said motor by operating said electric motor in generator mode. 
     
     
       5. The hybrid drive system as claimed in claim 2, wherein said sensors to sense parameters indicative of the state of said battery includes a battery temperature sensor to sense battery temperature of said battery, a battery voltage sensor to sense voltage at terminals of said battery and a battery current sensor to sense flow of electric current during discharge and charge from and to said battery. 
     
     
       6. The hybrid drive system as claimed in claim 2, wherein said sensors to sense parameters indicative of the state of said engine includes an engine speed sensor to sense a parameter indicative of speed of rotation of said engine and an engine coolant temperature sensor to sense temperature of the engine coolant. 
     
     
       7. A method for the management of an electric motor for powering an electric motor of a vehicular hybrid drive system including a fuel powered engine, comprising: sensing parameters indicative of a state of a battery;   sensing parameters indicative of a state of the engine;   deriving information of a state of charge (SOC) of the battery from said sensed parameters indicative of the state of the battery;   determining based on said sensed parameters indicative of the state of the engine whether or not the engine is being powered by fuel; and   conducting a forced discharge from the battery, by establishing supply of electric energy from the battery to the electric motor when the state of charge (SOC) of the battery is greater than or equal to a predetermined value, thereby to cause the electric motor to start up the engine unless the engine is being powered by fuel and to operate in power mode after starting up the engine.   
     
     
       8. A method for the management of a battery to power an electric motor of a hybrid drive system for a vehicle, comprising: sensing parameters indicative of the state of the battery;   deriving information of the state of charge (SOC) of the battery from said sensed parameters indicative of the state of the battery; and   deriving information of battery temperature of the battery and information of the state of charge (SOC) of the battery from said sensed parameters indicative of the state of the battery,   conducting a forced discharge from the battery by establishing supply of electric energy from the battery to the electric motor when the battery temperature is less than or equal to a predetermined temperature value and the state of charge (SOC) of the battery is greater than or equal to a predetermined SOC value,   conducting a forced charge to the battery by establishing supply of electric energy to the battery from the electric motor when the battery temperature is less than or equal to said predetermined temperature value and the state of charge (SOC) of said battery is less than said predetermined SOC value.